Stress-induced morphology and fine-line stability enhancement of NiSi on poly-SiGe with a buffer polycrystalline silicon interlayer

Abstract

The thermal and morphological stability of NiSi is enhanced by inserting a polycrystalline ͑poly-Si͒ buffer layer between the Ni and poly-SiGe films. NiSi films formed on poly-Si/poly-SiGe stack layers possessed continuous, smooth structures after annealing at 500-850°C. Moreover, nickel germanosilicide ͓Ni͑Si, Ge͔͒ lines formed on the poly-SiGe exhibited a fine-line effect, i.e., the sheet resistance increased upon decreasing the linewidth, whereas the sheet resistance of NiSi lines formed on the poly-Si/poly-SiGe stack layers remained less than 5 ⍀ / square. A model for the stress-confined grain growth and recrystallization is proposed to explain the improved properties of the poly-Si-buffered film.